Prior art plows used for the same purpose differ in structure, and each type has certain advantages. However, the interbody clearance between adjacent plow bodies in all such plows, which determines the plow length, is in excess of an admissible value which can ensure minimum overall length of the plow without disrupting normal operation of the plow, in particular, without interfering with the furrow slice passage between the plow bodies.
Known in the art is a widely used two-way plow comprising a carrier frame supporting a frame rotatable about the longitudinal axis which carries left-handed and right-handed bodies and moldboard jointers as well as colters and landsides attached to the bodies.
Therefore, the two-way plow differs from a normal hiller plow for carrying out a one-sided (normally, right-handed) dumping of furrow slices only in the provision of a rotatable frame and a double set of working members, the design and relative position of which determine the length of the two-way plow. The working members of the two-way plow correspond to the design and relative position of the working members of a hiller plow in which the interbody clearance is determined by the presence of a moldboard jointer throwing the cut top part of the furrow slice into an open furrow which is formed by the body positioned ahead thereof.
The need for a double set of working members in the two-way plow is a disadvantage, and certain technical solutions were sought for eliminating this disadvantage.
In plows which are free this disadvantage of the two-way plow is overcome in that the carrier frame supports a horizontally rotatable frame carrying plow bodies attached thereto, each plow body ensuring both left- and right-handed dumping of the furrow slice.
Known in the art are two types of plow bodies for such plows.
A body of the first type comprises an integral left- and right-handed moldboard having a pair of shares whose front tips are conjugated or separated by land edges. Depending on the desired direction of dumping of the furrow slice, the share is mounted to the left or to the right with respect to a leg of the body by means of a pivot joint having its pivot pin disposed at the intersection of the vertical plane of symmetry of the leg and the plane of symmetry of the moldboard.
This type of plow body is deficient due to enlarged linear dimensions of the moldboards in the vertical direction so that it is difficult to use such plow bodies for a large plow width. In addition, the configuration of the moldboards (cylindrical or conical) cannot be adapted for operation under all soil conditions.
It is preferred to have another type of plow body in the form of a composite body having front and rear symmetrical parts mounted for rotation for left-handed and right-handed dumping of the furrow slice.
Thus known in the art is a plow body having a leg in the front part thereof which supports front parts of the left- and right-handed moldboards with shares, which are mounted in the working position in a mirror-like relation relative to a transverse vertical plane drawn through the axis of rotation of the leg, the rear part of the body being configured as a freely rotatable concave cylinder.
However, the rear part of this plow body which is made shorter to reduce the interbody clearance in the plow, hence to reduce the plow length, results in a poor turning of the furrow slice, i.e. in a lower quality of plowing during operation of the plow.
Also known in the art is a plow body having a leg in its front part which supports a common left- and right-handed front part of a moldboard with a share which is symmetrical with respect to a plane extending through the axis of rotation of the leg and the middle of the share, the rear part supporting rear parts of left- and right-handed moldboards which are mounted in a mirror-like relation to each other. Depending on the desired direction of dumping of the furrow slice, the front and rear parts of the plow bodies are turned in such a manner that, upon an appropriate rotation of the frame, one of the side edges of the moldboard is in registry with the side edge of the rear part of a respective moldboard, whereby a full moldboard is formed for left- or right-handed dumping of the furrow slice (U.S. Pat. No. 3,305,025).
This plow body can easily comply with any requirements imposed upon plowing. However, the use of this plow body in a prior art plow having a horizontally rotatable frame cannot allow the plow length to be reduced due to a reduction of the interbody clearance to a value which is only determined by the furrow slice passage between the bodies, i.e. to the admissible value which is determined by purely process requirements.
The reason for this is that the rotatable frame of this plow is mounted on the carrier frame for pivoting about a vertical axis at the same angle in both directions, whereby, when the rotatable frame is mounted in the working positions, the rear parts of the plow bodies are turned in such a manner that the interbody clearance is limited by purely structural considerations because it is necessary to allow the rear parts of the plow body to be turned without interference with the bodies located therebehind, provided the plow does not have moldboard jointers and colters the use of which would make the plow length still larger.
Consequently, the plow having the horizontally rotatable frame has only one set of working members which makes it advantageous over a two-way plow from the point of view of material saving; at the same time, the need to ensure the turning of the furrow slice by each body alternately in both directions results in a complicated structure of the plow body and calls for the provision of an actuator means for setting the plow bodies to the working positions.
In spite of promising developments associated with the advent of manufacture of the plow having a horizontally rotatable frame, the problem of reducing its length while retaining the conventional parameters of the plow bodies and the use of moldboard jointers and colters could not be solved in such a plow because of disadvantages caused by the design of the rotatable frame.
Swinging of the frame at one and the same angle in both directions with respect to a longitudinal vertical plane is the main disadvantage not only of the abovedescribed plow, but of all conventional plows having a horizontally rotatable frame irrespective of the plow body type. It is this disadvantage that does not allow the interbody clearance in such plows to be reduced and shorter plows to be provided.